Portable collapsible shelters, e.g., folding canopies, can be designed for ease of transport, setup, and takedown. Such shelters can be useful for outdoor gatherings, temporary military posts, emergency cover, even indoor conferences or trade shows to provide a sense distinction from other exhibits, among other uses.
Portable collapsible shelters can include accordion-type collapsible truss assemblies between supporting legs of the shelter. According-type collapsible truss assemblies can include a number of truss members interconnected at pivotal x-joints near truss member midpoints and at pivotal v-joints near truss member endpoints. The truss members may be connected at one endpoint to a portion of a shelter leg, e.g., at a slidable or fixed mounting bracket, and at another endpoint to another truss member at a pivotal v-joint. Thus, the accordion-type collapsible truss assembly can be expanded and collapsed to allow for ease of transport, setup, and takedown.
Truss assemblies for portable collapsible shelters were initially composed of thick walled steel tubing. In the push for lighter weight and ease of portability, some manufacturers have used lower strength materials, e.g., aluminum. However, aluminum is typically more expensive and weaker than steel. As a result of the desire to limit weight and cost, some manufacturers have also used thin walled truss members in portable collapsible assemblies.
The use of lighter weight, lower strength materials in collapsible truss assemblies has led to deformation and failure of truss members, particularly near pivotal x-joints. Such deformation can be caused, at least in part, by user abuse in forcing the operation of setup and takedown, or weather related axial bending stresses, among other causes. Due to the nature of some designs of the collapsible truss assembly, loading can centralize near the midpoint of truss members at the pivotal x-joints, potentially leading to the above-described defects.